The overall goal is to determine whether enteropathy due to bacterial enteric infection is a primary cause of sudden infant death. Experiments will evaluate the hypothesis that infection of he infant gut by the pathogenic bacterium Clostridium perfringens can result in the production of enterotoxin(s). The absorption and subsequent action of the enterotoxin is influenced by a membrane bound activator whose presence is age related. The presence of this activator and the mechanism of action of the enterotoxin are determinants in sudden death. The specific aims of the research project are: 1. To purify and characterize an activator for C. perfringens 8-6 enterotoxin from rabbit ileal tissue. 2. To determine how the activator influences the action of C. perfringens 8-6 enterotoxin in mice of different ages by examining changes in time to death, alterations to ileal tissue in vivo, and alterations to Vero cells in vitro. 3. To examine the incidence of C. perfringens in SIDS and non-SIDS infants and to examine ileal tissue from these infants for histopathological damage as an indicator of enteropathy. The importance of this study is that the hypothesis under examination accounts for he major pathophysiologic and epidemiologic observations of SIDS. If our hypothesis is correct then SIDS due to enteric infection by C. perfringens should largely be preventable by immunization.